MUSCLE-STIFFNESS DURING TRANSIENT AND CONTINUOUS MOVEMENTS OF CAT MUSCLE - PERTURBATION CHARACTERISTICS AND PHYSIOLOGICAL RELEVANCE
MUSCLE-STIFFNESS DURING TRANSIENT AND CONTINUOUS MOVEMENTS OF CAT MUSCLE - PERTURBATION CHARACTERISTICS AND PHYSIOLOGICAL RELEVANCE
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DOI：
10.1109/10.310091
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发表时间：
1994-08-01
影响因子：
4.6
通讯作者：
RYMER, WZ
中科院分区：
文献类型：
--
作者：
KIRSCH, RF;BOSKOV, D;RYMER, WZ
在肌肉和反射研究中，连续的随机位置扰动是一种有吸引力的替代瞬时扰动的方法，因为它们允许有效地表征系统特性。然而，从随机扰动获得的结果的相关性仍然不清楚，因为它们可能会导致肌肉属性的状态变化。我们通过比较由随机扰动引起的去大脑猫的孤立肌肉的力量和僵硬反应，以及由类似幅度的“台阶”伸展引起的反应，解决了这个问题。研究发现，在随机扰动过程中，对于给定的工作点，肌肉的刚度主要是线性的和弹性的，即使在大的运动中，也没有证据表明瞬时的幅值相关的非线性。相比之下，阶跃拉伸引起的力响应在性质上主要是粘性的，在较大的拉伸时是非线性的，只有很小的保持(弹性)分量。对于随机摄动和阶跃摄动，刚度值均随着位移幅值的增大而减小。我们的结果与肌肉收缩的交叉桥理论基本一致，表明瞬时和连续的位移引起肌肉行为的不同方面，尽管在功能上是相关的。这些差异对姿势和运动的神经控制以及为其研究设计适当的扰动有几个含义。
Continuous stochastic position perturbations are an attractive alternative to transient perturbations in muscle and reflex studies because they allow efficient characterization of system properties. However, the relevance of the results obtained from stochastic perturbations remains unclear because they may induce a state change in muscle properties. We addressed this concern by comparing the force and stiffness responses of isolated muscles of the decerebrate cat elicited by stochastic perturbations to those evoked by ''step'' stretches of similar amplitudes. Muscle stiffness during stochastic perturbations was found to be predominantly linear and elastic in nature for a given operating point, showing no evidence of instantaneous amplitude-dependent nonlinearities, even during large movements. In contrast, force responses evoked by step stretches were found to be mainly viscous in nature and nonlinear for larger stretches, with only a small maintained (elastic) component. Stiffness magnitude decreased with displacement amplitude for both stochastic and step perturbations. Our results are largely consistent with the crossbridge theory of muscle contraction, indicating that transient and continuous displacements evoke different, although functionally relevant, aspects of muscle behavior. These differences have several implications for the neural control of posture and movement, and for the design of perturbations appropriate for its study.